Vietnam-Era Aircraft Aged But Able;

A Sandstorm Or Smoke From Burning Oil Wells May Have Contributed, Officials Said.

The CH-46 Sea Knight helicopter that crashed Friday morning in Kuwait, killing 12 American and British soldiers, was part of an aging U.S. Marine Corps fleet that is long overdue for retirement.

The cause of the crash, at 7:47 p.m. EST Thursday about nine miles from the Iraqi border, is unknown. But officials say it was not shot down.

Although the CH-46 has been transporting Marines since the Vietnam War, a series of crashes and safety concerns in the past decade have underscored the need for a replacement.

"This problem of aging inventory exists across the board," said John Williams, spokesman for the National Defense Industrial Association, a lobby group for the defense industry. "It does predispose people to accidents that they would not have been exposed to if this inventory had been replaced earlier."

The crash killed four Marine crew members from Camp Pendleton, Calif., and eight British commandos. The pilot, a member of the 3rd Marine Aircraft Wing, was identified as Capt. Ryan Beaupre, 30, of St. Anne, Ill. The identities of the other crew members had not been released.

Reports have speculated that smoke from burning oil wells or a sandstorm may have played a role in the crash.

The CH-46 went out of production in 1971 and was scheduled to be phased out by 1999. But safety problems with its replacement, the V-22 Osprey, has the future of both helicopters in limbo.

That leaves the Marines with no choice but to keep flying their fleet of nearly 300 CH-46s into combat, where they are used primarily to transport troops and equipment.

The CH-46 is older than most of the pilots who fly them, said Master Sgt. Dwaine Roberts, a spokesman at the Marine Corps Air Station Miramar in San Diego.

"And that's why we are consistently and proactively seeking a replacement aircraft -- that effort has been ongoing for the past 15 to 20 years," Roberts said. "It is a safe aircraft, but it is an older aircraft, and we definitely are looking for a replacement."

Last August, the entire fleet of CH-46s was grounded when a crack was found in the motor assembly of a helicopter. An inspection of the fleet found only one other helicopter with a similar problem.

That grounding followed one in February 2001, also because of a crack in a rotor assembly.

There have been at least four CH-46 crashes since 1996 that have killed 24 servicemen.

The Osprey, however, also has been involved in fatal crashes linked to design flaws and criticism that it is too expensive. In 1990, then-Secretary of Defense Dick Cheney canceled the Osprey program, but he was overruled by Congress.

More recently, the Osprey testing was halted after two crashes in 2000 killed 23 Marines. The Osprey can take off and land like a helicopter but, with rotors that tilt forward after takeoff, also can cruise at the speed of an airplane.

But until the safety problems are fixed, Department of Defense officials say they will keep the Osprey from going to full production.

Some critics of the Osprey say the helicopter program should be scrapped because its design already is 20 years old.

Unlike the Osprey, the CH-46 is a battle-tested warhorse that has proved itself over the long haul, said Patrick Garrett, a defense analyst with Globalsecuri ty.org, a Washington think tank.

"At the moment, it [the CH-46] seems to be a much better alternative than the Osprey," Garrett said. "On the other hand, the CH-46 is an aging helicopter; it's technology is widely obsolete."

But scrutinizing the CH-46 because of this week's accident might be unfair, considering that flying a helicopter into combat is inherently dangerous, he said.

The CH-46 typically flies at less than 100 feet to avoid radar and antiaircraft fire. At speeds up to 166 mph and that close to the ground, there's little margin for error, said Larry Buynak, a retired Marine helicopter pilot who served during the first Gulf War.

"Flying in that desert is very challenging. It's very difficult -- the dust in the air blends in with the sand; there's really no horizon -- you're flying on instruments," he said.

"The CH-46 is an old aircraft but it's a good aircraft," he said. "If I were there right now, that's what I'd be flying and I'd be perfectly comfortable doing so."

GRAPHIC: PHOTO: In Doha, Qatar. Al Lockwood, a Royal Air Force group captain, addresses the media Friday about the crash that killed 12 American and British troops.